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    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 100px;
            height: 200px;
            background-color: aquamarine;
            transition: all 0.5s;
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        div:hover {
            height: 500px;
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</head>
<body>
    <div>
        <ul>
            <li>
                <div class="nav-tab">技术分析</div>
                <ul class="nav-menu">
                    <li>音视频</li>
                    <li>语言</li>
                    <li>Firebase</li>
                    <li>Google AAB</li>
                    <li>百度</li>
                </ul>
            </li>
        </ul>
    </div>
</body>
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